Abstract

Summary and Conclusions

During a study of the natural occurrence of poliovirus infections in southern Louisiana, 115 families were kept under continuous observation during the 3 years, 1954–1956. In this period 207 isolations of E7 virus were made in relation to 55 distinct episodes of household infection. Of these, 40 occurred in 1956, apparently reflecting a major but silent epidemic of E7 infection. Analysis of the age-immunity profile and of the annual and seasonal occurrence of infection in the study group and of the infection and immunity patterns within households suggests a very close parallelism between the occurrence of E7 virus infection and that of any single poliovirus type.